1. Technical Field of the Invention
The present invention pertains to a method and apparatus for acquiring visual images and/or other data in a wellbore or other environment. More particularly, the present invention pertains to a method and apparatus for acquiring visual images and/or other data in a wellbore or other environment while providing improved illumination of said environment.
2. Brief Description of the Prior Art
Downhole camera systems exist for obtaining video and/or visual images in wellbores, pipelines, tanks, vessels or other similar environments. However, most wellbores or other environments contain little or no existing source of ambient or available light. Accordingly, a light source must be provided to illuminate downhole portions of said environments when acquiring visual data in such areas is desired.
Certain existing camera systems utilize some form of quartz lamp(s) to illuminate downhole portions of a wellbore or other similar environment for purposes of visual data acquisition. In one example, an incandescent light bulb is placed behind a camera body with a reflector. In another example, a low voltage, low power incandescent lamp is used to reduce the power requirements. In yet another example, certain downhole camera systems utilize an array of light-emitting diodes (LEDs) placed around the lens of a camera.
However, placing a light source behind a camera with a reflector causes a large dark section to appear on the acquired visual images; such dark section is caused by the body of the camera being positioned in front of the light source. Such a configuration may be generally acceptable in certain environments (such as, for example, large diameter pipe). However, as the size of a surrounding pipe is reduced, problems with existing light source systems typically increase. Especially in smaller pipe, a camera functions as a light choke, preventing light from entering in the camera's field of view.
Placing light bulbs or LEDs around a camera lens also causes several other problems. Heat from the lamps or LEDs typically causes electronic noise and damages the quality of the images coming from the camera. Camera sensor electronics are also typically rendered inoperable and/or damaged in higher temperature operating environments. Additionally, shining lights directly into fluids or at the top of the object to be viewed can also cause a back-scatter of light resulting in glare or shine spots, further reducing the quality of the images captured.
Thus, conventional lighting designs deployed in downhole camera systems generally fall into two categories: (1) a light source is positioned behind a camera or image sensor; or (2) a circular array comprising a ring light is positioned around a camera or image sensor. With the first option, light projecting from a rearward position tends to cast a distinct shadow on the inspection subject of interest, thereby reducing the quality of captured visual images. With the second option, bulk lamps and LED modules packaged around a camera add to the outside diameter of the imaging instrument, thereby limiting overall effectiveness and versatility, particularly in wells having relatively narrow internal diameters. The type of lighting in the second option is also considered to be ‘direct’ lighting and causes exponentially more shadows than a diffused lighting system.
In many cases, oil and gas wells and/or other industrial applications involve confined areas with very limited space. Such environments are best served by slim profile equipment that can traverse small tubing sizes and other restrictions. However, housing a high-powered, high-heat dissipating light source within proximity to a temperature-sensitive camera, image sensor and/or associated electronics has represented a long standing design challenge.
Thus, there is a need for a slim-profile camera and illumination assembly that can be beneficially used in wellbores or other environments lacking sources of ambient or available light. The camera and illumination assembly should be robust enough to function in harsh or difficult environments, and should beneficially illuminate a field of view (and a subject of interest therein) in order to improve the quality of captured visual images.
Further, the camera and illumination assembly should permit a high-powered, high-heat dissipating light source to be housed within proximity to the temperature-sensitive camera, image sensor and/or associated electronics, without degrading or negatively impacting performance thereof. Additionally, there is a need for a method of diffusing the light so as to minimize backscatter reflections and improve the quality of captured visual images.